Numerical model of an Yb:Er:Tm:Ho co-doped germanate glass: concentrations optimization and transfer function

In this paper, we numerically simulate the population of levels of an Yb:Er:Tm:Ho co-doped germanate glass pumped at 980 nm, that could be able to generate broad emission in a wavelength range from 1500 nm to 2100 nm. The aim of this work is to study the possibility of reaching a homogeneous inversion of Er, Tm and Ho, in order to further develop ultra-broadband active devices. We study the influence of a variation in the concentration of the dopants in such a complex system, which exhibits many energy transfer phenomena between different rare earth ions. Furthermore, we computed the transfer function of the system to evaluate the pump noise influence.